As a process for producing a quinolinecarboxyaldehyde derivative, JP-A-1-279866, EP-A-304063 and U.S. Pat. No. 5,011,930 disclose a process which comprises reacting 2-amino-4′-fluorobenzophenone with ethyl isobutyrylacetate to obtain a quinolinecarboxylate derivative, once reducing it with diisobutylaluminum hydride to obtain a quinolinemethanol derivative, and further oxidizing it with pyridinium chlorochromate to obtain an aimed quinolinecarboxyaldehyde derivative. However, this production process comprises a large number of steps and is not advantageous as an industrial production process.
The present invention is to provide a process which makes it possible to produce 2-cyclopropyl-4-(4′-fluorophenyl)quinoline-3-carboxyaldehyde of the following formula by an industrially advantageous simple process. 